1) Field of the Invention
The present invention relates generally to a seat belt system for a utility vehicle, and, more specifically, to a simplified circuit for verifying that a vehicle operator observes the proper sequence of positioning on the seat and seat belt fastening.
2) Related Art
In vehicles such as skid steer loaders and similar utility vehicles, there is a need to provide a seat belt system that verifies that the operator follows the proper procedure at the operator station which includes first sitting in the vehicle seat and then fastening the safety belt to assure that the operator cannot merely sit on a fastened belt. Further, the seat belt system must have the capability to prevent resetting of logic circuitry if the operator momentarily bounces out of the seat. Circuits including microcontrollers may be used for such seat belt systems, but the microcontroller requires filtered and reduced regulated voltage rather than direct battery voltage, which adds complexity and cost to the system. A circuit in a utility vehicle often must be able to operate over voltage extremes which can vary from a minimum of several volts to jump start voltages several times the minimum.
Another problem associated with belt and seat sequence circuits is assuring recognition of the proper order of events before or after the key switch is turned to the on position without causing significant current drain when the switch is off. If a warning signal such as a panel light can be lit with the switch off, the battery can be inadvertently discharged.